let checkEmail = (email) => {
    let checkEmail = /^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+$/;
    if (checkEmail.test(email))
        return true;
    else
        return false;
}

function getOrientation(file, callback) {
    var reader = new FileReader();
    reader.onload = function(e) {

        var view = new DataView(e.target.result);
        if (view.getUint16(0, false) != 0xFFD8) {
            return callback(-2);
        }
        var length = view.byteLength,
            offset = 2;
        while (offset < length) {
            if (view.getUint16(offset + 2, false) <= 8) return callback(-1);
            var marker = view.getUint16(offset, false);
            offset += 2;
            if (marker == 0xFFE1) {
                if (view.getUint32(offset += 2, false) != 0x45786966) {
                    return callback(-1);
                }

                var little = view.getUint16(offset += 6, false) == 0x4949;
                offset += view.getUint32(offset + 4, little);
                var tags = view.getUint16(offset, little);
                offset += 2;
                for (var i = 0; i < tags; i++) {
                    if (view.getUint16(offset + (i * 12), little) == 0x0112) {
                        return callback(view.getUint16(offset + (i * 12) + 8, little));
                    }
                }
            } else if ((marker & 0xFF00) != 0xFF00) {
                break;
            } else {
                offset += view.getUint16(offset, false);
            }
        }
        return callback(-1);
    };
    reader.readAsArrayBuffer(file);
}

export default {
    checkEmail,
    getOrientation
}